
I had to trim the wiper bracket to get the box to fit.

I laid out a box on an old Priority Mail envelope, cut it out and taped it together to see how it fit.

I really suck at taking pictures as I go but here's the current mockup.

Right now the tab on back is slated to be cut off since the charger I plan to use will hit the wiper assembly.

The unit is about 1 3/4" deep so I'm not sure it'll work on the box itself. I may mount it just inside the hole, I'll have to see how hard it would be to use there. It looks like the widest you can make the box is 2 1/2" if you plan to use the arms on the front to hold the box. My plan is to make the front tall enough to use both the handle screws and the arms to secure it to the front.

You can probably make the box 7" deep but no more than that since it'll hit the passenger side wiper arm. The slide itself is out of the way.

The angle on the face of the dash is about 22 degrees.

Tomorrow if I can find a battery that isn't flat or hard to get to I'm going to cycle the wipers to check clearances. Once I see where things are at I'll finalize my design and post the measurements I end up with.